Formation of potato tubers is a complex developmental system which includes important biological processes such as growth regulator level changes, synthesis of specific proteins and starch deposition. Tuber formation is controlled by short day and low temperature conditions. Axillary buds of potato stem can also produce tubers in in vitro conditions. Considering these facts the first sign of starch deposition during early development of microtubers in axillary buds of potato (Solanum tuberosum L. cv. ΄Bintje΄) has been investigated. Potato plantlets used in the experiment were microcloned by nodal segments on MS medium with 2% sucrose and 0.8% agar in 4 week intervals. Stem segments were transferred on mod. MS medium for tuberization supplemented with 8% sucrose, 0.8% agar and 22 μM BA. Cultures were maintained at 20 ºC under short day conditions (12 hr photoperiod). For hystological analysis buds were taken every day for 14 days, fixed and stained with Lugol solution (IKI2) before embedding in glycerole. The first sign of starch deposition was noticed on day three in the basal part of axillary buds on tuber stimulative medium. In explants grown under same conditions but on medium without BA starch deposition was not noticed even after 14 days in culture. Four days after the occurence of the first starch deposition axillary buds were thickened and formed oval microtubers in next days. This confirms the importance of high sucrose concentrations and BA presence in nutrient medium as well as short photoperiod and temperature in the tuberization process of potatoes.