Abscisic acid and proline levels in tobacco plants can help determine their ability to withstand drought. Drought-tolerant plants accumulate these substances faster than drought-sensitive ones when leaf water potential drops. Abscisic acid builds up before proline in both types of plants. Drought-tolerant plants reach critical water potential levels sooner due to their higher cell wall elasticity. Proline levels sharply increase at around -1.27 MPa in drought-tolerant plants and -1.50 MPa in drought-sensitive ones. Abscisic acid concentrations rise significantly at -0.77 MPa, with higher levels in drought-tolerant plants. These findings suggest that monitoring abscisic acid and proline levels could be useful for selecting drought-tolerant tobacco varieties.