This thesis sets out to increase our knowledge of mechanisms by which lung cancer cells develop resistance to chemotherapeutic agents. To further investigate drug resistance in lung cancer, a panel of four cell lines were chosen for pulse-selection with chemotherapeutic agents. The cell lines include two squamous (SKMES-1 and DLRP) and two small cell lung carcinoma (DMS-53 and NCI-H69) cell lines. The chemotherapy naive cell lines were pulse-selected rather than continuously selected with clinically relevant concentrations of taxotere, taxol, carboplatin and/or VP-16. The resulting twelve novel cell lines were tested for resistance to a cross-section of chemotherapeutic agents, for changes in invasiveness, motility, adhesiveness and for expression of the multidrug resistance (MDR) efflux pump proteins, P-gp and MRP-1. The SKMES-taxane selected variants were chosen for further analysis because the resistance profile was unstable and the concentration of drug used for selection was at a clinically achievable level. Proteomic analysis was used to identify proteins associated with the development of taxol and taxotere resistance m these cell lines Proteomic analysis also revealed the differences between resistance to taxol and taxotere. Loss of resistance was observed in both taxane resistant variants of SKMES-1. By monitoring the differential protein expression over time, proteins involved in the loss of resistance were identified. Adriamycin and mitoxantrone resistance was also studied in the squamous lung cell line DLKP. While the main mechanism of resistance in these cell lines is associated with a drug pump, little information on cytoplasmic changes is available Proteomic analysis investigated these changes and elucidated the mechanisms involved in adriamycin and mitoxantrone resistance to identify putative markers with possible prognostic/diagnostic value. A comparison of the proteins altered in adriamycin and mitoxantrone-resistant variants was carried out as these drugs are intercalating agents with mitoxantrone being an analogue of adriamycin and inducing less cardiotoxicity. Multidrug resistance is a major problem in lung cancer, there is a need to understand the common mechanisms involved. The proteins involved in the development of taxane resistance in SKMES-1 showed some cross over with other chemotherapeutic drugs namely adriamycin or mitoxantrone in DLKP.