Highly effective and powerful antiviral drugs have been introduced into clinical practice in recent years which are associated with an increased incidence of nephrotoxicity. The need of combining several drugs, the fragility of the patients treated, and the high susceptibility of the kidney are all factors contributing to renal injury. Many pathogenetic mechanisms are involved in the nephrotoxicity of antiviral drugs, including drug interaction with transport proteins in the tubular cell; direct cytotoxicity due to a high intracellular drug concentration; mitochondrial injury; and intrarenal obstruction or stone formation due to the low solubility of drugs at a normal urinary pH. As a result, various clinical pictures may be observed in patients treated with antiviral drugs, ranging from tubular dysfunction (Fanconi syndrome, renal tubular acidosis, nephrogenic diabetes insipidus) to acute renal failure (induced by tubular necrosis or crystal nephropathy) and kidney stones. Careful attention should be paid to prevent renal toxicity by evaluating the glomerular filtration rate before therapy and adjusting the drug dosage accordingly, avoiding the combination with other nephrotoxic drugs, and monitoring renal parameters on a regular basis while treating patients.