Background: Hyperparathyroidism is a common problem secondary to renal insufficiency and is often not entirely resolved after renal transplantation (TX). Methods: In this retrospective analysis, the effects of parathyroidectomy (PTX) on allograft function were evaluated and the risk factors involved in allograft deterioration in patients after PTX will be discussed. Results: The rise in creatinine was steeper 1 year after PTX compared to 2 years before PTX in the majority (13 of 22) of patients. Compared to a cohort without PTX, graft survival was significantly decreased by 60% in 6 years (p < 0.0001). After multivariate adjustment, risk factors attributed to graft function included baseline creatinine (p = 0.02), baseline systolic blood pressure (p = 0.04) and time between TX and PTX, but not PTX itself. The peri-PTX drop in serum calcium was significantly more accentuated in patients exhibiting a worsening of graft function after PTX (p = 0.04). Conclusions: In patients requiring PTX, graft function is in danger of worsening. Since many factors contribute to this negative correlation and no association with parathyroid hormone (PTH) levels before PTX has been observed, we do not recommend prophylactic PTX on the basis of PTH levels only. However, appropriate management of peri-PTX risk factors is highly important. If the clinical situation, e.g. progressive renal osteodystrophy, requires removal of parathyroid glands, the procedure should be performed, if possible, in the presence of stable graft function.