The main aim of the present thesis is to develop Glipizide solid lipid nanoparticles (Glip-SLNs) for improving its bioavailability, therapeutic efficacy and increasing duration of action. Eight different formulae of Glip. -SLNs were produced by HSH and sonication technique. Solubility study was performed on different lipids including Beeswax, Compritol® 888 ATO, Precirol® ATO 5 and stearic acid to identify appropriate lipids for formulation of Glip.-SLNs. Particle size, PDI, zeta potential, %DC, %EE, %DL, % PY and in-vitro release parameters (t50 and t90) were taken as responses to detect the optimized formula. The results indicated solubility of Glip. in Compritol® 888 ATO and Precirol® ATO 5 which have low Hydrophilic-lipophilic balance (HLB). A valid HPLC method for analysis of Glip- SLNs showed the retention time of Glip. was 4.1 min. and the method was linear over a range of 1-20 µg/ml. Formula (SLN7) which composed of precirol as lipid base, span 60 as lipid surfactant, lutrol F 127 as aqueous surfactant and methocel E5 (1%) as viscosity increasing agent was the optimized formula. Particle size, PDI, ZP, % DC, % EE, % DL, % PY, t50 and t90 for optimized formula were 217 nm, 0.307, -13.80 mV, 99.29 %, 93.45%, 60.32%, 95.82%, 17.68 hrs. and 31.75 hrs. respectively. On comparing oral bioavailability of Glip- SLNs (SLN7) with marketed product (Minidiab® 5 mg tablet) as tested by the rate of change in blood glucose level (E) in wistar rats after single oral dose, the bioavailability of (SLN7) has 2.50 folds increase than marketed product. Results of Liquid Chromatography Mass Spectrometry (LC-MS) for analysis of SN7 and marketed product in plasma of wistar rats showed percentage relative bioavailability (PRBA) of Glip. - SLNs (SLN 7) in comparison to marketed product (Minidiab® 5 mg tablet) was 413.00 %.