Context: Limb lengthening has its own share of problems, obstacles, and complications, which is of great concern when used for a cosmetic indication. Aims: This study explores safe limits for cosmetic tibial lengthening and examines how age of the patient and length gained influences osteogenesis and complications. Settings and Design: This was a retrospective analytical study. Subjects and Methods: We reviewed 70 consecutive cases (140 segments) of monofocal tibial cosmetic lengthening with minimum of 1-year follow-up operated between 2006 and 2010. Statistical Analysis Used: We correlated patient's age and percentage by which bone was lengthened with external fixator index (EFI) and occurrence of obstacles and complications and did receiver operator characteristic (ROC) curve analysis to determine the safe limit. Results: Mean age of patients was 27 (16–52) years. Mean tibial lengthening was by 16.5% (4.1–27.9) of the preoperative length. Sixty segments faced 76 difficulties comprising 16 problems, 47 obstacles, and 13 complications. Patient's age positively correlated with EFI, but did not correlate with the incidence of obstacles and complications. Percentage by which bone was lengthened negatively correlated with EFI and positively correlated with incidence of obstacles and complications. ROC curve analyses (with optimum balance of sensitivity and specificity) revealed lengthening by more than 18.1% and 16.4% to be significantly associated with the occurrence of complication and more than one obstacle, respectively. Conclusions: In cosmetic tibial lengthening, increasing age increases the duration of external fixation and increased lengthening increases obstacles and complications. Great caution must be exercised in cosmetic tibial lengthening beyond 16%.