Urolithiasis is a rare but familiar problem in transplanted kidney patients, with a prevalence rate between 0.23-6.3%. Minimally invasive percutaneous nephrolithotomy (mini-PCNL) is a revised technique that uses a miniature endoscope through a small access sheath and is associated with minor bleeding risk. Only a few cases of mini-PCNL via ultrasonography (US) guidance in transplanted kidneys have been published. We present a 23-year-old female and a 34-year-old man who presented with obstructive uropathy due to impacted stones in their transplanted kidneys. Firstly, the nephrostomy tube was inserted. Then, they underwent mini-PCNL via US guidance. Puncturing the pyelocaliceal system was achieved via a 3.5 MHz US probe. Procedures were performed with a one-shot dilatation technique and a 15-Fr rigid nephroscope. In conclusion, we suggest that if an experienced urologist performs it, the US-guided mini-PCNL is safe and effective in patients with transplanted kidneys.